Left panel: CMD focusing on the eMSTO region of NGC 1783. The MUSE targets are represented as large circles, color-coded according to their v sin i values. The dashed red box outlines the selection region for UV-dim stars (see text), which are highlighted by open red circles. Central panel: v sin i of the eMSTO targets in the magnitude range 19.6 < m_F814W < 21.2 as a function of the verticalized color. The dashed red line marks the selection edge for the UV-dim stars, corresponding to Δ(m_F275W − m_F438) = 0.16, with the selected UV-dim stars indicated by red circles. Right panel: normalized histograms of the v sin i distributions for the stars shown in the central panel. The gray histogram represents the eMSTO stars, while the red histogram shows the v sin i distributions for the subsample of UV-dim stars.